Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic sulfur compound – wherein the sulfur is single bonded...
Reexamination Certificate
2002-01-23
2003-11-11
Howard, Jacqueline V. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic sulfur compound, wherein the sulfur is single bonded...
C508S391000, C508S460000, C508S574000
Reexamination Certificate
active
06645922
ABSTRACT:
This invention concerns a lubricating oil composition suitable for use in a two-stroke cross-head marine diesel (compression-ignited) engine. The lubricating oil composition comprises a base oil and a metal detergent additive.
One type of marine diesel propulsion engine is characterised as a slow speed, two-stroke engine which is frequently referred to as a cross-head engine because of its construction. The firing cylinder and crankcase are lubricated separately by cylinder and system oils respectively. The cylinder oil, sometimes referred to as a marine diesel cylinder lubricant (MDCL), is fed to the internal walls of the cylinder by injection and, unlike the system or crankcase oil, is consumed. This invention is concerned with lubrication of the crankcase, bearings and, gears and valve-train system (if required), or system lubrication.
A paper entitled “Cylinder and System Lubricating Oil Qualities and New Engine Development” made public by MAN B & W, a leading manufacturer of cross-head marine diesel engines, in November 2000, reports recent developments in the design of such engines as requiring original equipment manufacturer (OEM's) to improve the efficiency of the oil-cooling of the pistons. The system oil performs such oil-cooling and is required to control piston temperatures which tend to rise due to the higher engine loads that are being imposed.
Improved cooling-efficiency requires the oil to dispose of more heat thereby placing new demands on it in terms of oxidation and high temperature deposit control. The above paper recognises that some commercial system oils fail to meet these demands.
The present invention ameliorates the above problem by providing the detergency for system oils by use of a complex detergent rather than non-complex detergents as known in the art. The examples of this specification show a remarkable and surprising improvement when using a complex detergent.
Accordingly, a first aspect of the invention is a lubricating oil composition suitable for a two-stroke cross-head marine compression ignited (diesel) engine system, the lubricating oil composition comprising:
(A) a base stock of lubricating viscosity, in a major amount; and
(B) an oil-soluble overbased metal detergent additive, in a minor amount, in the form of a complex wherein the basic material of the detergent is stabilised by more than one surfactant.
A second aspect of the present invention is a method of providing system lubrication to a two-stroke cross-head marine compression ignited (diesel) engine which comprises lubricating the crankcase of the engine with the lubricating oil composition as defined in the first aspect of the invention.
A third aspect of the present invention is a combination of the crankcase of a two-stroke cross-head marine compression-ignited (diesel) engine and the lubricating oil composition as defined in the first aspect of the invention.
A fourth aspect of the present invention is a method of improving the oxidation control of a two-stroke cross-head marine compression-ignited (diesel) engine system lubricant which comprises using, as a detergent in the lubricant, a detergent as defined in the first aspect of the invention.
In this specification, the following words and expressions shall have the meanings ascribed below:
“major amount”—in excess of 50 mass % of the lubricant, preferably in excess of 60 mass %, more preferably in excess of 70 mass %;
“minor amount”—less that 50 mass % of the lubricant, both in respect of the stated additive and in respect of the total mass % of all the additives present in the lubricant, reckoned as active ingredient of the additive or additives; preferably less than 40 mass %, more preferably less than 30 mass %;
“active ingredient (a.i.)” refers to additive material that is not diluent;
“comprises or comprising, or cognate words”—specifies the presence of stated features, steps, integers or components, but does not preclude the presence or addition of one or more other features, steps, integers, components, or groups thereof;
“TBN”—Total Base Numbers as measured by ASTM D2896;
“oil-soluble or oil-dispersible”—do not necessarily indicate solubility, dissolvability, miscibility or capability of suppression in oil in all proportions. They do mean, however, solubility or stable dispersibility sufficient to exert the intended effect in the environment in which the oil is employed. Moreover, additional incorporation of other additives may permit incorporation of higher levels of a particular additive, if desired.
It will be understood that the various components of the lubricating oil composition, essential as well as optimal and customary, may react under the conditions of formulation, storage or use and that the invention also provides the product obtainable or obtained as a result of any such reaction.
The features of the invention will now be discussed in more detail as follows:
Two-Stroke Cross-Head Marine Diesel Engine
The engines may, for example, have from 6 to 12 cylinders and their engine speed may, for example, be in the range of from 40 to 200, preferably 60 to 120, rpm. Their total output may, for example, be in the range of 18,000 to 70,000 kW.
Lubricating Oil Composition
The lubricating oil composition may, for example, have a TBN of 2 or greater, preferably, 5 or greater; more preferably in the range of from 2 to 8, preferably 5 to 8. Such lubricating oil compositions because they are rarely, if ever, changed, need to be resilient and may be characterised by superior or particular strength against wear, corrosion, oxidation, and water centrifugation.
The lubricating oil composition may, for example, have a kinematic viscosity at 100° C. (as measured by ASTM D445) of at least 10, preferably at least 11, more preferably in the range from 10 to 12. The lubricants are usually SAE30 oils.
(A) Base Stock (Base Oil) of Lubricating Viscosity
The base stock is an oil of lubricating viscosity (sometimes referred to as base oil) and may be any oil suitable for the system lubrication of a cross-head engine. The lubricating oil may suitably be an animal, vegetable or a mineral oil. Suitably the lubricating oil is a petroleum derived lubricating oil, such as a naphthenic base, paraffinic base or mixed base oil. Alternatively, the lubricating oil may be a synthetic lubricating oil. Suitable synthetic lubricating oils include synthetic ester lubricating oils, which oils include diesters such as di-octyl adipate, di-octyl sebacate and tri-decyl adipate, or polymeric hydrocarbon lubricating oils, for example, liquid polyisobutene and poly-alpha olefins. Commonly, a mineral oil is employed. The lubricating oil may generally comprise greater than 60, typically greater than 70, % by mass of the lubricating oil composition and typically have a kinematic viscosity at 100° C. of from 2 to 40, for example from 3 to 15, mm
2
s
−1
, and a viscosity index from 80 to 100, for example from 90 to 95.
Another class of lubricating oil is hydrocracked oils, where the refining process further breaks down the middle and heavy distillate fractions in the presence of hydrogen at high temperatures and moderate pressures. Hydrocracked oils typically have kinematic viscosity at 100° C. of from 2 to 40, for example from 3 to 15, mm
2
s
−1
and a viscosity index typically in the range of from 100 to 110, for example from 105 to 108.
The term ‘brightstock’ as used herein refers to base oils which are solvent-extracted, de-asphalted products from vacuum residuum generally having a kinematic viscosity at 100° C. from 28 to 36 mm
2
s
−1
and are typically used in a proportion of less that 30, preferably less than 20, more preferably less than 15, most preferably less than 10, such as less than 5, mass %, based on the mass of the lubricating oil composition.
(B) Complex Overbased Metal Detergent
A detergent is an additive that reduces formation of piston deposits, for example, high-temperature varnish and lacquer deposits, in engines; it has acid-neutralising properties and is capable of keeping finely divided solids in suspension.
Chambard Laurent
Dunn Adrian
Owen Yolanda
Howard Jacqueline V.
Infineum International Ltd.
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